U.S. patent application number 11/508300 was filed with the patent office on 2007-03-29 for ultrasound guidance system.
This patent application is currently assigned to ULTRASOUND VENTURES, LLC. Invention is credited to Scott P. Jarnagin, Colin Kelemen, Todd M. Korogi, Theodore J. Mosler, Paul Nuschke, Robert Park, Bryan J. Peters.
Application Number | 20070073155 11/508300 |
Document ID | / |
Family ID | 37809380 |
Filed Date | 2007-03-29 |
United States Patent
Application |
20070073155 |
Kind Code |
A1 |
Park; Robert ; et
al. |
March 29, 2007 |
Ultrasound guidance system
Abstract
A compact ultrasound needle guidance system and method of use is
described. The needle guidance system has components to adjustably
target a needle's destination in the plane of a two-dimensional
ultrasound image before insertion of a needle into a patient.
Needle movement is tracked using a position detector that provides
a visual display of the needle path on the ultrasonic image.
Inventors: |
Park; Robert; (Durham,
NC) ; Kelemen; Colin; (Wilmington, NC) ;
Nuschke; Paul; (Durham, NC) ; Mosler; Theodore
J.; (Raleigh, NC) ; Jarnagin; Scott P.;
(Raleigh, NC) ; Korogi; Todd M.; (Raleigh, NC)
; Peters; Bryan J.; (Raleigh, NC) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
ULTRASOUND VENTURES, LLC
Durham
NC
|
Family ID: |
37809380 |
Appl. No.: |
11/508300 |
Filed: |
August 23, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60808552 |
May 26, 2006 |
|
|
|
60714192 |
Sep 2, 2005 |
|
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Current U.S.
Class: |
600/461 |
Current CPC
Class: |
A61B 8/0833 20130101;
A61B 8/4455 20130101; A61B 8/0841 20130101; A61B 8/4218 20130101;
A61B 46/10 20160201; A61B 2017/3413 20130101; A61B 17/3403
20130101; A61B 8/4472 20130101 |
Class at
Publication: |
600/461 |
International
Class: |
A61B 8/00 20060101
A61B008/00; A61B 17/34 20060101 A61B017/34; A61B 8/14 20060101
A61B008/14 |
Claims
1. An ultrasonic probe, comprising: a transducer adapted for
generating ultrasonic images of a scanning plane; and a needle
guide coupled to the transducer and rotatable within a plane that
is perpendicular to a body surface to be penetrated by a needle
received in the needle guide, wherein the plane is not parallel to
the scanning plane.
2. The probe of claim 1, wherein the needle guide is rotatable
about an axis that is in a plane parallel to the scanning
plane.
3. The probe of claim 1, wherein the probe is a hand-held
probe.
4. The probe of claim 1, including an angular position detector for
detecting angular displacements of the needle guide about the
axis.
5. The probe of claim 4, wherein the angular position detector
includes one of a potentiometer and a position encoder.
6. The probe of claim 4, wherein the transducer comprises the
angular position detector.
7. The probe of claim 6, wherein the needle guide is connected to a
shaft, the angular position detector is coupled to the shaft and
the angular position detector detects angular displacements of the
shaft.
8. The probe of claim 4, wherein the angular position detector
detects angular positions of the needle relative to the scanning
plane.
9. An ultrasonic probe, comprising: a transducer adapted for
generating ultrasonic images of a scanning plane; a member mounted
to the transducer and configured to rotate about an axis that is in
a plane parallel to the scanning plane; a position detector coupled
to the member; and an arm configured to receive a needle holder,
connected to the member and extending outwardly from the transducer
so that a needle to be received in the needle holder can be rotated
about the member axis.
10. The probe of claim 9, wherein the needle guide is configured so
that a needle inserted into the needle guide pivots within a plane
that is perpendicular to a body surface to be penetrated by the
needle and the scanning plane.
11. The probe of claim 9, wherein the probe is a hand-held
probe.
12. The probe of claim 9, wherein the transducer is contained
within a sterile shell.
13. The probe of claim 9, wherein the transverse plane is normal to
the scanning plane.
14. The probe of claim 9, wherein the arm rotates in only one
transverse plane.
15. An apparatus for tracking a position of a needle relative to an
ultrasonic image, comprising; a hand-held ultrasonic probe having a
scanning plane; a needle guidance portion including a needle holder
coupled to the probe for rotation about an axis that is in a plane
parallel to the scanning plane, the needle holder defining a needle
path originating at the needle holder and extending through the
scanning plane; and a circuit for determining an intersection of
the needle path and the scanning plane using needle path data
generated by the needle guidance portion.
16. The apparatus of claim 15, wherein the circuit locates an
intersection of the needle path and the scanning plane in response
to incremental movement of the needle holder.
17. The apparatus of claim 16, wherein the circuit calculates a
distance from the probe to the intersection of the needle path and
the scanning plane using the needle path data and distance between
the needle holder and scanning plane.
18. The apparatus of claim 15, wherein the intersection of the
needle path and scanning plane is computed from the angle through
which the needle holder rotates and the position of the needle
holder relative to the transducer.
19. A display in combination with the apparatus of claim 15, the
display including an ultrasonic image generated from the ultrasonic
probe, and a visual indicia of the needle path generated from the
needle path data.
20. A method for positioning a needle for treatment of a target
body within a patient using a hand-held ultrasonic probe having a
scanning plane, comprising the steps of: mounting a needle on the
probe, the needle having an angular position relative to the
scanning plane; placing the hand-held probe on the patient;
displaying a two-dimensional image of the scanning plane including
the target body, the image including a visual indicia of an
anticipated needle position relative to the target body; rotating
the needle about an axis that is in a plane parallel to the
scanning plane while monitoring the corresponding movement of the
visual indicia; and when the indicia is aligned with the target
body, placing the needle at the target body.
21. The method of claim 20, wherein the placing the probe step is
performed using a first hand and the rotating the needle step is
performed using a second hand.
22. The method of claim 20, further comprising moving the visual
indicia towards the target by rotating the needle.
23. The method of claim 20, wherein the placing the needle step is
performed after the visual indicia is coincident with the target on
the display.
24. The method of claim 20, further including obtaining depth
insertion information for determining the insertion depth of the
needle into the patient, and inserting the needle to a depth
according to the depth insertion information.
25. The method of claim 20, wherein the placing the needle step
includes inserting the needle into the patient in a direction
transverse to the scanning plane.
26. A method of tracking a position of a needle relative to a
target body, comprising the steps of: providing a hand-held
ultrasonic probe having a scanning plane; mounting a needle on a
needle guide of the probe, the needle having a needle path
extending from the needle to the scanning plane; rotating the
needle guide in a plane transverse to the scanning plane; and
determining an intersection of the needle path and the scanning
plane in response to rotation of the needle guide.
27. The method of claim 26, wherein the determining an intersection
of the needle path step includes generating needle position data as
a function of needle rotation.
28. The method of claim 26, wherein the generating needle position
data includes generating needle position data for a continuum of
angles through which the needle guide rotates.
29. The method of claim 26, wherein a shaft of the needle is
positioned for being displaced along the needle path so that the
shaft intersects the scanning plane.
30. The method of claim 26, further comprising the step of
displaying on a display an ultrasonic image and a visual indicia
representing the intersection of the needle path and the scanning
plane.
31. A system for locating a needle insertion point, comprising; an
ultrasonic probe having a scanning plane; a display showing an
ultrasonic image of the scanning plane generated by the probe; a
needle guide coupled to the probe for rotational motion relative to
the probe and about an axis that is in a plane parallel to the
scanning plane; a position detector coupled to the needle guide; a
circuit generating data from the position detector; and the display
further including a visual indication of an anticipated needle
position based on the circuit data and displayed with the
ultrasonic images.
32. The system of claim 31, wherein the probe is a hand-held
probe.
33. The system of claim 31, wherein the needle guide is configured
for receiving a shaft of a needle in a direction substantially
perpendicular to the axis.
34. The system of claim 31, wherein the position data is generated
in real-time so that rotational movement of the needle guide is
displayed as a moving visual indication of the needle position on
the display.
35. An ultrasonic probe, comprising: a needle clip coupled to a
transducer, the needle clip comprising: a cradle for a needle, and
an arm having an end that forms a cover; wherein the cover is
manually movable between a first position opening the cradle and a
second position closing the cradle; wherein the cover is detached
from the cradle in the second position and configured such that the
cover is retainable in the second position only when external
pressure is applied to the needle clip; and wherein when the cover
is in the second position, the cover and cradle together form a
passageway for a needle shaft disposable between the cover and
cradle such that the passageway allows movement of the needle in a
first direction and substantially prohibits movement of the needle
in a second direction that is perpendicular to the first
direction.
36. The probe of claim 35, wherein the cover is devoid of a
mechanical engagement with the cradle when in both the first and
second positions so that the cover is retainable in the first
position or the second position only upon application of an
external pressure to the needle clip.
37. The probe of claim 36, wherein the first end resists movement
of the cover between the first position and the second
position.
38. The probe of claim 35, wherein when the arm is in the second
position, the needle is substantially prohibited from movement in
the first direction by an interference fit between the cover and
cradle.
39. The probe of claim 35, wherein the probe is a hand-held
probe.
40. The probe of claim 35, wherein when the cover is in the first
position the first end is undeformed and when the cover is in the
second position, the first end is deformed by pressure applied to
the arm, and wherein when the pressure on the arm is relieved, the
cover returns to the first position by only the elastic energy
stored in the first end.
41. The probe of claim 40, wherein the first end is one of a
substantially L-shaped and straight member.
42. A method of releasably fastening a needle to an ultrasonic
probe, comprising the steps of: providing a needle clip on the
probe, the needle clip including a displaceable cover and a cradle
adapted to receive a needle shaft; placing the needle shaft within
the cradle; applying pressure to the cover such that the cover
moves from a first position distal of the cradle to a second
position proximal to the cradle, whereupon the needle is held
between the cradle and cover; and relieving the pressure on the
cover, whereupon the cover moves from the second position to the
first position.
43. The method of claim 42, wherein the applying pressure step
includes deforming a member connected to the cover at a first end
thereof and the releasing the pressure step includes restoring the
member to its un-deformed state such that the cover is returned to
the first position by only the elastic energy stored in the
deformed member.
44. A sterile shell for an ultrasonic probe, comprising: a first
shell portion; a second shell portion; a third shell portion
defining a chamber for receiving an end of the ultrasonic probe; a
first living hinge connecting the first and third shell portions;
and a second living hinge connecting the second and third shell
portions.
45. The sterile shell of claim 44, further including an acoustic
coupling gel sealed within the chamber.
46. The sterile shell of claim 44, further including a window for
allowing passage of a clip connector of a probe received within the
shell.
47. The sterile shell of claim 44, wherein each of the first,
second and third portions are formed so as to be substantially
rigid.
48. A method of encasing an ultrasonic probe in a sterile shell,
comprising the steps of: providing a sterile shell, including a
first, second and third shell portion, a first living hinge
connecting the first and third shell portions, a second living
hinge connecting the second and third shell portions, and the third
shell portion having a chamber containing a gel; removing a cover
from the third shell portion; placing a waveguide of the probe
inside the third shell portion; and placing the second and first
shell portions over the probe, thereby enclosing the probe within
the shell.
49. The method of claim 48, wherein the providing step includes
providing a rigid shell.
Description
FIELD OF INVENTION
[0001] The present invention relates generally to ultrasound
systems and, more particularly, to ultrasound guidance systems.
This application claims priority under 35 U.S.C. .sctn. 119(e) to
U.S. Provisional Application No. 60/714,192 filed Sep. 2, 2005 and
U.S. Provisional Application No. 60/808,552 filed May 26, 2006.
BACKGROUND OF INVENTION
[0002] As an inexpensive and noninvasive technique, ultrasound is
useful as a medical imaging modality able to provide real time
feedback in a two-dimensional fashion at a patient's bedside.
Ultrasound facilitates dozens of procedures performed in hospitals
and clinics every day, with these procedures ranging from breast
biopsies to central line catheter insertion to amniocentesis.
[0003] In a typical ultrasound guided procedure, a doctor will
place a small, handheld probe known as a transducer on a patient's
skin. The transducer converts electrical energy to acoustic energy.
Acoustical energy is transmitted from the transducer and into the
patient's body in the form of sound waves. The transmitted sound
waves are either reflected back towards the transducer or absorbed
by the medium, depending on the acoustical impedance. For example,
a bone or fat, having relatively high acoustical impedance,
reflects the sound waves with little or no attenuation of the sound
wave, while a vein or artery, having a relatively low impedance,
will absorb acoustical energy. The reflected sound waves are
converted into electrical signals which are used to form a real
time two-dimensional image of a portion of the patient's body.
[0004] This image may be used to assist a health professional with
locating a region of the patient's body for purposes of locating
the point where an invasive medical device, e.g., a needle, is
inserted. After locating the correct insertion point, the health
professional may then begin the medical procedure, such as
insertion of a catheter, administration of a local anesthetic, or
removal of tissue as in a biopsy.
[0005] It is sometimes difficult to accurately track the path and
position of the medical device after it has entered the patient's
body on the monitor. The medical device, e.g., a needle, is not
typically visualized by the ultrasound image, which is essentially
a two-dimensional image. Unless the needle is positioned exactly
in-plane with the image, the needle is not visible or only
partially visible, which means that the needle location or, more
importantly the location of the needle tip, is not known exactly.
As such, a health professional will often make numerous attempts to
insert the device before he or she can see the target tissue mass
or blood vessel buckle under the force of the needle pressing
against it. And in the case where the target is, for example, a
nerve, the health professional often times can only estimate the
location of the needle end if it is not visible on the ultrasound
image. Such an error-prone, user-dependent procedure is painful for
the patient, time consuming for the health professional, and incurs
possible additional liability for the hospital with each use.
Procedures for using an ultrasound imaging device for peripheral
nerve blocks are described in Anna Dabu BScH, and Vincent W S Chan,
MD, FRCPC A Practical Guide to Ultrasound Imaging For Peripheral
Nerve Blocks (copyright 2004 by Vincent W S Chan, MD, FRCPC), the
contents of which are incorporated herein by reference in its
entirety.
[0006] There are multi-planar ultrasound imaging devices capable of
producing a three-dimensional image of the body, which may be
capable of more accurately locating the position of an invasive
medical device, but these types of devices are typically expensive
to operate, and require a relatively high degree of skill and
training to operate. It would be desirable if a low-cost device,
capable of being used effectively by a health professional with
moderate or little training in ultrasound imaging techniques, were
available which could accurately locate the position of the medical
device beneath the skin. This would eliminate much of the
"guesswork" that is involved in locating a medical device at the
point of interest.
[0007] Existing ultrasound devices can be characterized by the
approach of the needle-guided insertion with respect to the plane
of the ultrasound beam. In the "transverse" type, the medical
device, e.g., needle, is orientated out of plane and is sometimes
disfavored because visualization of the needle is not reliable as
it passes through the patient's body. The "longitudinal" type has
the added advantage of seeing the entire length of the needle
because it is inserted in plane with the ultrasound beam; however,
it can be difficult to keep the needle in the plane of the
transducer image due to operator skill and inherent needle-bending
when passing through tissue.
[0008] While the longitudinal type device is preferred because
there is greater chance of tracking the needle, it is also more
difficult to position the needle at the target when the needle is
planar with the image. A transverse needle pathway, on the other
hand, is more intuitive, is shown to be easier for novice
ultrasound users, and is the preferred approach for various
procedures according to experts. The following three studies have
been conducted which compare the performance of longitudinal verses
transverse type of ultrasound guidance devices, all of which are
incorporated herein by reference: P. Marhofer, M. Greher and S.
Kapral, Ultrasound guidance in regional anesthesia, British Journal
of Anasthesia 94 (1): 7-17 (2005); M. Blaivas, L. Brannam, and E.
Fernandez, Short-axis verses Long-axis Approaches for Teaching
Ultrasound-guided Vascular Access on a New Inanimate Model, ACAD
Emerg Med, Vol. 10, No. 12 (December 2003); and B. D. Sites, J. D.
Gallagher, J. Cravero, J. Lundberg, and G. Blike The Learning Curve
Associated With a Simulated Ultrasound-Guided Interventional Task
by Inexperienced Anesthesia Residents, Regional Anesthesia and Pain
Medicine, Vol. 29, No. 6 (November-December 2004), pp. 544-548.
[0009] One known ultrasound device for assisting a health
professional with needle placement in a body is the ilook.TM.
personal imaging tool, sold by SonoSite, Inc., which includes a
series of removable needle guides. The device is used to place a
needle at a target location beneath the skinline by real-time
visual identification of the target via an ultrasonic image. A
bracket, located on the front of the transducer, is used to mount a
needle guide. The needle guide is orientated such that a needle
received therein will extend approximately perpendicular to the
sonic scanning plane. Thus, the SonoSite, Inc. device is a
transverse-type device. When it is time to perform the procedure,
the device is wrapped in a sterile sleeve (an acoustic coupling gel
is put into the sleeve and the sleeve is placed over the
transducer) and the sleeve is sealed using a rubber band. The
sleeve covers the transducer and bracket. The procedure for use
includes inserting the acoustic coupling gel into the sleeve,
covering the device with the sleeve, ensuring there are no cuts or
tears in the sleeve, then securing the sleeve with a rubber band.
After this sterilization of the transducer, a sterile needle guide
is snap-fit on the bracket. There is more than one-type of needle
guide to choose from. The choice depends upon the distance between
the skinline and the top of the vessel. Three choices are available
for this particular device: a 1 cm, 2 cm and 3 cm needle guide that
reflect an approximate depth of the target vessel beneath the
skinline. These different lengths correspond respectively to
increasing angular inclinations of the needle relative to the
skinline.
[0010] The needle guide has a door that can be locked in a closed
position by a slidable switch, thereby retaining the needle shaft
between the door and a semi-circular recessed area. The needle is
placed in this recessed area and the door is closed to hold the
needle therein. The transducer with needle is then placed on the
skinline and the top of the vessel is located via the sonic image.
The needle is then inserted into the body.
[0011] After the needle has reached the target, the transducer
needs to be removed from the needle, which requires unlatching the
door of the needle guide. This procedure can cause complications as
it is often necessary to maintain precise positioning of the needle
within the body. When the door is being unlatched, there can be
unacceptable motion of the transducer (and therefore of the needle)
as a result of overcoming mechanical resistance in the latch.
[0012] Another known ultrasound imaging device is the
Site-Rite.RTM. Ultrasound System by Bard Access Systems. This
device also provides a needle guide to hold the needle at a fixed
angle with a transverse approach and is operated in a similar
manner as the SonoSite, Inc. device described above. A health
professional first places the transducer such that a target of
interest (e.g. a vessel's lumen) is visible on the screen. The
location of the target is then estimated and a needle guide is
selected such that the needle will pass closest to the target's
location. Because the entire probe is enclosed in a sterile sleeve,
the needle guide is typically disposable and kept sterile until
use. When needed, the needle guide is clamped to the probe through
the sterile sleeve. Each needle guide is set to a static angle
which is not adjustable. If the insertion angle needs to be
corrected, the needle guide must be removed and substituted with a
different needle guide. Additionally, after inserting the needle
into the target, the probe must be rocked to pry the needle from
the needle guide, potentially disrupting the needle-target
interaction. This is because the needle guide is a one piece needle
guide with lips that are flexed to release the probe from the
needle.
[0013] U.S. Pat. No. 6,695,786 discloses a longitudinal-type
ultrasound device for biopsy procedures. The device has a biopsy
needle guide coupled to an ultrasound probe. The needle guide has a
needle holder connected to the probe by a link assembly that allows
a user to rotate the biopsy needle, but without allowing the user
to twist or bend the needle outside the imaged plane. Other
examples of longitudinal-type devices are described in U.S. Pat.
No. 4,058,114 and U.S. Pat. No. 4,346,717.
[0014] Known ultrasound monitors are typically fixed to a stand. In
these systems, a health professional often must turn his or her
head to focus on the screen. Also, these devices have cords
connecting the ultrasound probe to the monitor which are typically
much longer than needed for most procedures because it must be
sufficiently lengthy for extreme cases. As a result, the cord can
often obstruct the probe's user. Additionally, the probe cannot be
maintained in a sterile condition when it is placed on a holder
provided with the system.
[0015] There is a need for a user-friendly ultrasound system that
requires only a relatively low-degree of training and/or skill in
ultrasound imaging techniques. It would also be desirable to have a
device that reduces the error rate and/or discomfort to the patient
when locating targets during invasive procedures, and that offers
health professionals the ability to direct needles to a target of
any depth when the needle is controlled in a plane perpendicular to
the scanning plane. It would also be desirable to have a device
that is capable of being used in any invasive procedure without
additional health costs charged by a health provider; a device that
can be pre-aimed at a target and before insertion into a living
body; a device that provides easy visibility of the ultrasound
image and medical device in real time; and a device that is adapted
for releasably fastening an invasive medical device to a probe or
imaging device so as to reduce incidences of displacement of the
medical device within the patient's body when the medical device is
separated from the probe or medical device.
SUMMARY
[0016] The present invention is directed to an ultrasound needle
guidance system that facilitates placement of an ultrasound monitor
over a patient and ensures accurate and simple needle placement in
a target of interest within a patient's body. According to an
embodiment of the invention, a hand-held ultrasonic probe includes
a needle guidance position that holds a needle. The needle is
orientated transverse to the scanning plane of the transducer. The
needle can be rotated through a continuous range of angles and
these angular changes can be tracked and displayed as a cross-hair
(or other type of visual indicia) on a nearby monitor screen with
the ultrasonic image. In this way, a health professional can
accurately track and locate a needle to ensure precise placement at
a target within a patient's body.
[0017] In another embodiment, an ultrasonic probe includes a
hand-held body, a transducer contained within the body and adapted
for generating ultrasonic images of a scanning plane, and a needle
guide coupled to the body and rotatable about an axis that is in a
plane parallel to the scanning plane. The probe may include a
position detector for detecting the rotation of the needle.
[0018] In another embodiment, an ultrasonic probe includes a
hand-held body, a transducer contained within the body and adapted
for generating ultrasonic images of a scanning plane, a shaft
mounted within the body and configured to rotate through an angle
that is in a plane transverse to the scanning plane, a position
detector coupled to the shaft, and an arm configured to receive a
needle holder, connected to the shaft and extending out of the
body. The body may be a sterile shell of a body that holds the
transducer. The arm may be restricted to rotate within a transverse
plane.
[0019] In another embodiment, an apparatus for tracking the
position of a needle relative to an ultrasonic image includes a
hand-held ultrasonic probe having a scanning plane, a needle
guidance portion including a needle holder coupled to the probe for
rotation about an axis that is in a plane parallel to the scanning
plane, the needle holder defining a needle path originating at the
needle holder and extending through the scanning plane, and needle
path data generated by the needle guidance portion, wherein the
needle path data locates the intersection of the needle path and
the scanning plane.
[0020] In another embodiment, a method for positioning a needle for
treatment of a target body within a patient using a hand-held
ultrasonic probe having a scanning plane is provided. This method
includes the steps of mounting a needle on the probe, the needle
having an angular position relative to the scanning plane, placing
the hand-held probe on the patient, displaying a two-dimensional
image of the scanning plane including the target body, the image
including a visual indicia of the needle position relative to the
target body, rotating the needle about an axis that is in a plane
parallel to the scanning plane while monitoring the corresponding
movement of the visual indicia, and when the needle is aligned with
the target body, placing the needle at the target body. According
to this method, the needle may be placed at the target by rotating
the needle while tracking the movement of a visual indicia of the
needle's pathway on a display screen. Once the visual indicia
aligns with the target, the needle is positioned appropriately for
placement at the target.
[0021] In another embodiment, a method of tracking the position of
a needle relative to a target body includes the steps of providing
a hand-held ultrasonic probe having a scanning plane, mounting a
needle on the probe, the needle defining a needle path extending
from the needle to the scanning plane, rotating the needle guide in
a plane transverse to the scanning plane, and generating data
locating the intersection of the needle path and the scanning plane
in response to rotation of the needle guide. This method may
include the step of computing for a continuum of angles through
which the needle rotates the intersection of the needle path and
the scanning plane.
[0022] In another embodiment, a system for locating a needle
insertion point includes a display, a hand-held ultrasonic probe
defining a scanning plane, an ultrasonic image of the scanning
plane, generated by the probe and displayed on the display, a
needle guide coupled to the probe for rotational motion relative to
the probe and about an axis that is in a plane parallel to the
scanning plane, a position detector coupled to the needle guide,
position data generated from the position detector; and a visual
indication of the needle position generated from the position data
and displayed with the ultrasonic image on the display device.
[0023] In a preferred embodiment, the ultrasound system comprises a
height adjustable stand, an adjustable and moveable ultrasound
monitor, a retractable cord, and a system of hooks allowing probe
sterility while mounted on the ultrasound machine. Connected to the
ultrasound monitor is an ultrasound probe.
[0024] Preferably a removable sterile clip is used to mount the
needle to the probe. In this aspect of the invention, the clip is
configured to minimize mechanical noise associated with removal of
the probe from the needle. As such, it is preferred to use a clip
that does not rely on a mechanical engagement to retain the needle
in the needle clip.
[0025] In another embodiment of the invention, an ultrasonic probe
includes a needle clip that has a cradle for a needle and an arm
having a first end coupled to the cradle and a second end forming a
cover. In this embodiment, the cover is manually movable between a
first position opening the cradle and a second position closing the
cradle. Also, the cover is detached from the cradle in the second
position and when the cover is in the second position, the cover
and cradle together form a passageway for a needle shaft disposable
between the cover and cradle such that the passageway allows
movement of the needle in a first direction and substantially
prohibits movement of the needle in a second direction that is
perpendicular to the first direction.
[0026] In another embodiment of the invention, a method of
releasably fastening a needle to an ultrasonic probe includes the
steps of providing a needle clip on the probe, the needle clip
including a displaceable arm and a cradle adapted to receive a
needle shaft, placing the needle shaft within the cradle, applying
pressure to the arm such that the arm moves from a first position
distal of the cradle to a second position proximal to and
mechanically decoupled from the cradle, whereupon the needle is
held between the cradle and arm, and relieving the pressure on the
arm, whereupon the arm moves from the second position to the first
position. Alternatively, finger pressure may move the arm away from
the cradle so that when the finger pressure is relieved, the needle
is retained within the cradle.
[0027] Preferably, the ultrasound probe is encompassed by a thin
plastic sterile shell that allows access to a connector for
mounting the needle clip.
[0028] In still another embodiment, an apparatus for tracking the
position of a needle relative to an ultrasonic image includes a
hand-held ultrasonic probe having a scanning plane, a needle
guidance portion including a needle holder coupled to the probe for
rotation about an axis that is in a plane that is non-parallel with
the scanning plane and perpendicular to a body surface to be
penetrated by a needle received in the needle holder. For example,
the axis may lie in a plane that makes at least a 10, 15, 30, 45,
60, 75, between 45 and 90 degree, or up to 90 degree angle with the
scanning plane.
[0029] In another embodiment of the invention, a sterile shell for
an ultrasonic probe includes a first shell portion, a second shell
portion, a third shell portion defining a chamber for receiving an
end of the ultrasonic probe. Living hinges may be used to rotatably
connect the first, second and third shell portions together.
Additionally, an acoustic coupling gel may be contained within the
chamber and sealed until use by a removable lidstock, e.g., a
plastic wrapper or foil.
[0030] In another embodiment of the invention, a method of
sterilizing an ultrasonic probe includes the steps of providing a
sterile shell, including a first, second and third shell portion
connected to each other by living hinges, the third shell portion
defining a chamber containing a gel, removing a cover from the
third shell portion, placing a waveguide of the probe inside the
third shell portion, and placing the second and first shell
portions over the probe, thereby enclosing the probe within the
shell.
[0031] Among the various advantages apparent from the description,
there is provided a particularly useful apparatus and method for
administering a nerve block or performing an acute angle catheter
entry procedure.
[0032] These and other aspects of the present invention will become
apparent to those skilled in the art after a reading of the
following description of the preferred embodiment when considered
with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1A is a front view of a ultrasound guidance system
according to an embodiment of the present invention.
[0034] FIG. 1B is a side view of a monitor of the system of FIG.
1A.
[0035] FIG. 2 is a first front view of the monitor of FIG. 1B
showing an image generated by an ultrasound device and a cross hair
indicating a first angular orientation of a needle mounted to an
ultrasound device.
[0036] FIG. 3 is a second front view of the monitor of FIG. 1B
showing the same image generated by an ultrasound device and a
cross hair indicating a second angular orientation of the
needle.
[0037] FIG. 2A is a first side view of an ultrasound probe of the
system of FIG. 1A and needle mounted thereto corresponding to the
monitor image of FIG. 2, with the probe placed on a patient and
prior to inserting the needle into the patient and the probe is
enclosed in a sterile shell.
[0038] FIG. 3A is a second side view of the ultrasound probe of
FIG. 2A and needle mounted thereto corresponding to the monitor
image of FIG. 3, with the probe placed on the patient and after the
needle has been placed at a target within the patient and the probe
is enclosed in a sterile shell.
[0039] FIG. 4 is a side view of the ultrasound probe and sterile
shell of FIG. 1A.
[0040] FIG. 5 is a front view of the ultrasound probe and sterile
shell of FIG. 1A.
[0041] FIG. 5A is a perspective view of a portion of a needle
guidance portion of the system of FIG. 1A.
[0042] FIG. 5B is a schematic illustration of the processing steps
for needle positioning data according to an embodiment of the
present invention.
[0043] FIG. 6 is a perspective view of a second embodiment of an
ultrasonic probe enclosed in a sterile shell.
[0044] FIG. 7 is a perspective view of a sterile shell of the probe
of FIG. 6.
[0045] FIGS. 8A and 8B are first and second perspective views of
first and second parts of a first embodiment of a needle clip
according to the present invention.
[0046] FIG. 8C is a perspective view of the needle clip of FIGS. 8A
and 8B attached to the probe of FIG. 5.
[0047] FIG. 9 is a perspective view of a second embodiment of a
needle clip attached to the probe of FIG. 5 according to an
embodiment of the present invention.
[0048] FIG. 10 is a perspective view of a third embodiment of a
needle clip attached to the probe of FIG. 5 according to an
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0049] Referring now to the drawings in general, the illustrations
are for the purpose of describing preferred embodiments of the
invention and are not intended to limit the invention thereto. FIG.
1A shows a preferred cart-based compact ultrasound needle guidance
system 10. Among the features of system 10 is a monitor 20
(preferably an LCD monitor) that can be easily positioned for
optimal viewing during an ultrasound imaging process, and an
ultrasonic probe 30 that sends ultrasonic image data to monitor 20
via a cord 18. Probe 30 is preferably encased in a sterile shell 31
that completely encloses probe 30. Probe 30 includes a needle
guidance device, rotatably mounted to probe 30, which enables a
health professional to make angular adjustments to a needle mounted
to probe 30 during a procedure. Angular adjustments to the needle
are displayed on monitor 20 in real time with the ultrasonic image
so that the needle position can be tracked and aligned precisely
with the target located within the patient.
[0050] System 10 is lightweight, so that it may be moved about
without great difficulty. A stand 11 supports system 10, which may
include wheels to move it about the floor. Stand 11 is connected to
a height adjustable pole 13 which is connected at its upper end to
a rotatable arm 17. A tightening collar 12 fixes pole 13 at a
desired height and a lockable pivot 16 fixes arm 17 at a desired
angle relative to pole 13. Thus, in preparing system 10 for an
ultrasound procedure, monitor 20 is movable such that it can be
positioned directly in front of the user and over the patient. This
is accomplished by adjusting the height adjustable pole 13 and
pivoting the rotatable arm 17 about the lockable pivot. Once the
desired height is reached, height adjustable pole 13 and arm 17 are
locked into position by tightening collar 12 and pivot lock 16,
respectively. The mobility and lightweight properties of system 10
lend itself to easy height and angular adjustments by a single
health professional.
[0051] System 10 is designed to avoid occurrences of "drift" during
an invasive medical procedure using an ultrasound imaging device.
When a health professional must switch his or her attention from
the patient's body to the monitor (so as to track the progress of
the needle), the ultrasound device can become misaligned. System 10
avoids occurrences of drift by allowing selective placement of the
monitor in a position so that the health professional may maintain
his or her immediate attention on the patient and the
position/orientation of the ultrasonic probe 30 while viewing an
ultrasound image on monitor 20. Thus, system 10 may be operated so
that the probe and patient are within the same field of view as the
ultrasound image. This can reduce error rates, improve the accuracy
of the scan and or insertion of a needle and thus reduce the
discomfort to the patient and time taken for an invasive medical
procedure.
[0052] When arm 17 is moved and locked in place, monitor 20 may
require further adjustment so that the image appears in the correct
orientation relative to probe 30. This can be accomplished in one
of two ways. The ultrasound image may be oriented electronically by
rotating the image on the screen, or monitor 20 may be repositioned
by providing a pivotal mount for monitor 20 on arm 17 so that
monitor 20 may be tilted relative to arm 17. Either or both of the
above approaches may be followed in order to facilitate
adjustability of the image so that a health professional may obtain
an optimal viewing orientation of the ultrasound image.
[0053] Cord 18 is retractable within monitor 20 using a
spring-and-ratchet or similar mechanism. This allows cord 18 to be
pulled in and out of monitor 20 to a desired length. Alternatively,
a wireless communication link may be substituted for cord 18. In
this embodiment, probe 30 may further include a portable and
replenishable power source such as a rechargeable battery.
Referring to FIG. 1B, a latch or hook 15 is mounted to monitor 20
and pivotal about a rotatable mount 14. Probe 30 may be stored and
maintained in a sterile condition on hook 15 when not in use. A
ring or other suitable latching structure may be provided on cord
18 near probe 30 for latching to hook 15. If a wireless probe is
used, then a suitable latching device may be provided at the upper
end of probe 30. Hook 15, being mounted to a free pivot 15 that is
rotatable within the plane of the monitor screen, allows a latched
probe 30 to hang in a vertical position from monitor 20 regardless
of monitor 20 orientation. With this arrangement, system 10
provides a convenient location for storing probe 30 when it is not
needed, minimizes movement and operator error during a procedure,
and yet still maintains probe sterility.
[0054] FIGS. 4 and 5 illustrate side and front views, respectively,
of probe 30. Probe 30 includes an ultrasound transducer, which
generates the image data transmitted to monitor 20. This image data
is used to generate real time images of the patient's body below
the skinline. As shown, probe 30 is preferably encased within a
sterile shell 31 when performing a procedure. This ensures
sterility during a procedure. A sterile sleeve may also be used. In
an alternative embodiment, a sterile sleeve may be secured at an
upper end of probe 30 and extend upwardly to enclose cord 18. This
sleeve may be included with shell 31 or attached separately. As
described in greater detail, below, the transducer is conveniently
encased within sterile shell 31 by enclosing the transducer between
front and rear shell parts, and a front part which encloses the
forward end, i.e., the area designated by 37 in FIG. 5.
[0055] Probe 30 may be equipped with any suitably chosen,
commercially available transducer. For example, probe 30 may be
configured as a linear or curved array type and may be adapted for
scanning within high frequency bandwidths (e.g., 10-15 MHz) for
viewing near the skin surface or low frequency bandwidths (e.g.,
below 5-7 MHz) for viewing well below the skin surface. Ultrasonic
image data can be generated and processed for display on monitor 20
using any suitably chosen ultrasound system.
[0056] Acoustic signals are transmitted/received through a lower
surface 37 of the transducer such that a scanning plane B covers an
area below probe 30 as illustrated in FIGS. 4 and 5. At a lower end
of probe 30 there is a needle guidance portion 40. Needle guidance
portion 40 is used to mount a needle to probe 30 and permits a
health professional to make continuous angular adjustments to the
needle relative to scanning plane B during an ultrasound procedure.
Thus, system 10 does not require a health professional to
pre-select an angular orientation of the needle. Rather, a precise
angular orientation can be determined while an image is generated
of the area beneath the skin.
[0057] As seen in FIG. 5A, needle guidance portion 40 includes a
rotatable shaft 43 and a clip connector 44 extending
perpendicularly from shaft 43. Clip connector 44 extends through an
opening 35 formed on shell 31 so that it may releasably receive a
needle clip, e.g., needle clip 200 shown in FIG. 8C. The needle is
then mounted to needle clip 200. When mounted to needle guidance
portion 40, the needle may be rotated through a continuum of
angular positions relative to scanning plane B. In particular,
needle guidance portion 40 is arranged so that angular positions of
the needle are measured about an axis that lies in a plane parallel
to scanning plane B. Hence, probe 30 is configured for selectively
positioning a needle in a plane transverse to scanning plane B.
[0058] With reference to FIGS. 5, 5A and 8C, shaft 43 includes a
bearing 43a that is received within a housing 34 of shell 31. This
housing 34 permits rotational motion of shaft 43 and hence clip
connector 44 about an axis A (FIGS. 5 and 5A), which lies in a
plane parallel to scanning plane B. An opening 35 is formed on
housing 34 so that clip connector 44 may extend out from shell 31
and rotate through a predetermined range of angles. In another
embodiment, clip connector 44 may be disposed so that it is inset
from, or flush with opening 35 of shell 31. This embodiment may be
preferred since clip connector 44 is fixed to probe 30 and hence
not sterile. By having clip connector 44 recessed within opening
35, potential contamination of shell 31 may be avoided.
[0059] A needle clip 200 is attached to clip connector 44 by
placing clip connector 44 within a hollow post 224 formed on needle
clip 200 and engaging a snap-fit provided by depressions 44a formed
on clip connector 44 and mating ledges formed on inner surfaces of
post 224. Other means may be used for disengagably mounting clip
200 to clip connector 44. Needle clip 200 may also include a skirt
formed near a lower end of post 224. The skirt is intended to cover
opening 35 when needle clip 200 is mounted to clip connector 44,
without obstructing rotation of needle clip 200 about probe 30, so
as to further reduce the chance of contamination during a
procedure. A shaft of the needle is received in a cradle portion
204 of needle clip 200 and releasably held therein by a fastening
arm 216 during the procedure. The snap-fit engagement between post
224 and clip connector 44 is preferably easily releasable so as to
enable a health professional to remove needle clip 200 from clip
connector 44 after a procedure is completed. It is preferred that
needle clip 200 is a disposable needle clip and thus replaceable
after every procedure to maintain sterility. Needle clip 200 is
placed on clip connector 44 after the transducer of probe 30 has
been wrapped in a sterile sleeve or encased within a first
embodiment of a sterile shell 31 as shown in FIG. 5.
[0060] In the preferred embodiments, needle guidance portion 40
includes a needle tracking device that tracks the angular position
of the needle as it rotates about axis A. For example, in the
embodiment illustrated in FIG. 5A, a potentiometer 45 is rotatably
coupled to shaft 43 and used to determine angular displacements (or
velocities) of a needle as it rotates about axis A. Shaft 43 is
coupled to potentiometer 45 by, e.g., engaging a threaded end 46 of
shaft 43 with a rotor portion of potentiometer 45. It will be
appreciated that any suitably chosen, commercially available
tracking device may be used in place of potentiometer 45. For
example, shaft 43 may be coupled to a position encoder for
detecting angular motion of shaft 43. In another embodiment, needle
rotation relative to probe 30 may be accomplished using a living
hinge. Potentiometer 45 illustrated in FIG. 5A is part of a
potentiometer circuit (not shown) that transmits electronic signals
to a processor. These signals are used to produce real-time video
images of the needle's angular position relative to scanning plane
B. Position data from the potentiometer circuit may be transmitted
to monitor 20 separately from signals transmitted by the
transducer, or they may be combined into one signal. In one
embodiment, angular position data is processed separately from data
from the transducer using software associated with monitor 20 or a
separate computer connected to monitor 20. This software produces a
real-time, continuous image of the needle orientation that is
superimposed over the ultrasound image. In other embodiments,
transducer and angle measuring data may be processed simultaneously
so as to produce a single data stream that is fed to monitor 20.
The software used to process needle position information may be
incorporated into probe 30 or reside at a separate computer.
[0061] The schematic illustration of FIG. 5B describes one
embodiment of the steps that may be used to convert movement of the
needle mounted to probe 30 into a video image on monitor 20. As
shown, needle rotation through an angle .theta. is detected by the
angle detector, which in this example is a potentiometer. The
analog signal produced by potentiometer 45 is converted into a
digital signal. A digital position encoder may be used in place of
potentiometer 45. The digital signal is then converted into an
angle based upon stored potentiometer calibration data. This angle
data is then converted into a depth relative to the ultrasonic
image using stored X, Y offset parameters. These parameters are
obtained from calibration data and reflect the offset position of
the needle relative to scanning plane B. The depth position is then
combined with the ultrasonic image data and displayed on monitor
20, e.g., the cross-hair 62a illustrated in FIGS. 2 and 3.
[0062] Operation of probe 30 in connection with monitor 20 will now
be described with reference to FIGS. 2, 2A, 3 and 3A. FIGS. 2A and
3A illustrate side views of probe 30 with needle clip 200 secured
to clip connector 44 and a needle 50 received in needle clip 200.
Probe 30 is encased in sterile shell 31. A tip of needle 50 is
positioned adjacent to, but not penetrating the patient's skinline
C in FIG. 2A whereas in FIG. 3A the shaft of needle 50 is inserted
into the patient and properly located at target 64. FIG. 2A shows
needle 50 orientated at a first angle .theta..sub.1 relative to a
scanning plane B of the transducer and FIG. 3A shows needle 50
orientated at a second angle .theta..sub.2 relative to scanning
plane B. Dashed lines D and E represent the pathways for needle 50
when orientated at the respective angles .theta..sub.1,
.theta..sub.2 and distance .delta. in FIG. 3A is the distance along
pathway E from the skinline C that needle 50 must be inserted in
order to reach target 64. The term "needle pathway" refers to the
path needle 50 will take if inserted into the patient's skin at a
given angle relative to the scanning plane B. As can be seen in
FIG. 2A, needle pathway D intersects plane B above the intended
target 64 when orientated at angle .theta..sub.1. If needle 50 is
inserted at this angle, needle 50 will miss target 64. However,
when needle 50 is orientated at angle .theta..sub.2 relative to
scanning plane B, needle 50 will follow needle pathway E and
intersect scanning plane B at the target 64.
[0063] It is desirable to have both the correct needle pathway and
insertion depth identified before needle 50 is inserted. This will
minimize discomfort to the patient (caused by adjustments to the
needle position after the needle has penetrated the skin) and/or
simplify the process of positioning a needle at a target, which
reduces the skill level and time needed to place a needle at target
64. Moreover, it is important to know the depth of needle insertion
as this will increase the chances for effective administration of
the needle contents at a target and ensure that the needle tip does
not cause undue damage to neighboring tissue.
[0064] At present, the health professional often times has to rely
solely upon an ultrasound image of the living body, e.g., tissue
deformation such as buckling of a blood vessel wall, when deciding
whether or not the needle has reached the intended target. In cases
where there is no change in the ultrasound image of the living body
to indicate a needle location, e.g., when applying a local
anesthesia to block a nerve, a health professional must rely on his
or her knowledge of the patient's anatomy, which is only an
approximation. If a health professional could obtain accurate
information of both the needle pathway, target location and the
actual insertion depth of the needle, then the needle can be more
precisely placed at the target.
[0065] System 10 is configured to provide a health professional
with a visual indication of the needle pathway needed to intersect
plane B at the target 64 and the insertion depth needed to place
the tip of the needle at the target 64 (insertion distance
.delta.). FIGS. 2 and 3 show images 60a and 60b, respectively,
generated on monitor 20 that correspond respectively to the
position of probe 30 and needle 50 illustrated in FIGS. 2A and 3A.
Cross hairs 62a and 62b indicate the point of intersection between
the respective needle pathways D and E and scanning plane B. A
cross section of a blood vessel wall is also shown in FIGS. 2 and 3
with a section of the vessel wall corresponding to target 64. Image
60a indicates that the needle pathway D will intersect plane B
above target 64 (cross hair 62a), which means that needle pathway D
is too shallow. Image 60b indicates that the needle pathway will
intersect plane B at target 64 (cross hair 62b covers target 64),
which means that needle pathway E is the correct pathway for needle
50.
[0066] The insertion distance .delta. for needle 50 may be obtained
from the insertion angle .theta..sub.2 and other known distances
which may be stored with the X, Y Position Parameters discussed
earlier. For example, the insertion depth may be determined from
.theta..sub.2, the distance from surface 37 and target 64, the
horizontal distance between the needle shaft centerline (at the
needle clip) and the scanning plane B and the vertical distance
between the needle shaft centerline (at the needle clip) and the
bottom surface of probe 30. Once obtained, the needle insertion
depth may be matched to distance .delta. by providing score lines
on needle 50 or a stopper member that prevents needle 50 from being
inserted beyond the desired depth. For certain procedures, the
health professional may not need to know .delta. in order to ensure
accurate placement. For example, if needle 50 is intended for a
blood vessel wall, a visually identified buckling of the vessel
wall, flow of blood through the needle shaft passage or change in
resistance to needle 50 penetration may be sufficient to confirm
accurate placement. In other applications, such as when applying a
local anesthetic to block a nerve, knowledge of .delta. may be
useful in locating the target, or the health professional may again
rely on tissue changes in the ultrasonic image. On the ultrasound
screen, indirect or secondary signs of needle location may include
soft tissue deformation indicating that the needle is passing
through that tissue, and a hypoechoic acoustic shadow and ring down
artifact when the sound beam hits the needle. All of these
secondary signs are important when the needle itself is not
visualized. The crosshair (or another suitably chosen indicia) may
provide a focus point to watch for the formation of these secondary
signs. Since the needle pathway is shown on monitor 20, the health
professional can focus his or her attention on the cross hair. Once
the needle is located at the target by primarily visualizing the
needle itself or by one of the secondary indicators above, a small
portion of local anesthetic can be injected and may be detectable
by the reflected sound waves so that a change in the ultrasonic
image appears at the displayed cross hair. Likewise, once the
needle tip is placed at the target by direct visualization or by
secondary signs, the ultrasound guidance system can release the
needle and then the transducer can be orientated in parallel with
the needle insertion to visualize the entire length of the needle
including the tip in relation to the target.
[0067] With reference to FIGS. 2, 3, 2A and 3A, accurate
positioning of needle 50 with respect to its intended target 64
proceeds as follows. First, monitor 20 is positioned within the
health professional's immediate field of view of the patient and
ultrasound device, so as to avoid any occurrence of drift during
the procedure. If, initially, monitor 20 displays a cross hair,
e.g., cross hair 62a, above the target, then the needle pathway
needs adjustment. This is done by rotating the angle of insertion
of the needle 50 clockwise in FIG. 3A (of course, if cross hair 62a
were located below target 64, then needle 50 would be rotated
counterclockwise in FIG. 3A). This rotational motion is detected by
a change in resistance in the potentiometer circuit. The processed
signal produces real-time angular positional information for the
needle pathway which is represented on monitor 20 as a downwardly
moving cross-hair. As the needle pathway is adjusted downward by
rotating needle 50, cross-hair 62a moves downward and towards
target 64 until it reaches target 64, which corresponds to
cross-hair 62b. Once the cross-hair is centered on the target, the
desired needle pathway is located. It is desirable that, after the
needle pathway is found, clip is able to stay in the corresponding
position via a preset rotational resistance in shaft 43 of needle
guidance portion 40. Preferably, the rotational resistance is
provided to the shaft 43 by friction and a dampener coupled to
shaft 43. Alternatively, the potentiometer assembly may provide the
rotational resistance to shaft 43. Because the rotational
resistance holds the needle in place without user assistance, the
needle pathway can be reliably maintained. After needle pathway E
is found, needle 50 can be inserted the distance
.delta.(.theta..sub.2) where target 64 is located. Once at target
64, probe 30 may be removed from needle 50. After probe 30 has been
removed from needle 50, probe 30 may be set aside via the probe
mounting hook 15 which is attached to monitor 20, as discussed
earlier. Alternatively, probe 30 may be set aside onto the sterile
field via the sterile shell 31 and an optional sterile sleeve that
will extend down the length of the ultrasound cord 18. This
maintains probe and cord sterility in the event that probe 30 is
needed again. The remainder of the procedure may be performed in
usual sterile fashion.
[0068] Assembly of probe 30 includes calibration of the needle
guidance portion 40. That is, calibration of the changes in the
potentiometer circuit with respect to changes in the needle angle
and calibration of the angle data with depth positions on the
ultrasonic image, e.g., cross-hair locations relative to the image
plane displayed on monitor 20. It will be appreciated that the
potentiometer (or position encoder) may be calibrated using any
known method. After the angle data has been calibrated with respect
to changes in the potentiometer circuit, incremental angular
rotations of the needle may be determined from incremental changes
in the potentiometer circuit using any well known interpolation
algorithm. Depth position data, e.g., X, Y Offset Parameters of
FIG. 5B, are then computed. These depth position data include the
offset position of the needle pathway relative to the potentiometer
and the position of the potentiometer relative to the transducer.
These parameters are then used with the computed angular changes to
compute the depth positions, i.e., the intersection of the needle
pathway on the image plane.
[0069] As mentioned earlier, a needle guidance portion 40 is
arranged so that angular positions of the needle are measured about
an axis that lies in a plane parallel to a scanning plane B. Hence,
probe 30 is configured for selectively positioning a needle in a
plane transverse to scanning plane B. In other embodiments, angular
positions of the needle are measured about any axis that lies in a
plane perpendicular to a body surface to be penetrated by a needle
received in the guidance portion, but not a plane that is parallel
to the scanning plane. For example, angular positions may be
measured with respect to a rotation axis that lies in a plane that
makes at least a 10, 15, 30, 45, 60, 75, between 45 and 90 degrees,
or up to 90 degree angle with the scanning plane. In these
embodiments, the needle guidance portion may be constructed in a
similar manner to needle guidance portion 40, but with its mounting
to the transducer being such that the shaft about which the needle
rotates is orientated so that the needle rotates in a plane
perpendicular to a body surface to be penetrated by the needle but
not a plane that is parallel to the scanning plane. Such
embodiments can still offer the various advantages of the earlier
disclosed embodiments, such as tracking a needle position relative
to a target and aligning the needle with a target.
[0070] As mentioned, probe 30 is preferably encased in a sterile,
disposable shell 31. Shell 31 is configured with a housing 34 that
receives needle guidance portion 40, which is fit to an external
portion of the transducer and encases the entire transducer. When
fitting shell 31 to the transducer and needle guidance portion 40,
a front and rear shell portion may be used in which the front and
rear shell portions are brought together and held together by,
e.g., snap fasteners.
[0071] A second embodiment of a sterile shell is illustrated in
FIGS. 6 and 7. Shell 100, like shell 31 of the first embodiment, is
a clamshell formed to cover the entire probe. However, shell 100 is
formed to cover an embodiment of the ultrasonic probe where the
needle guidance portion is integrated into the transducer body.
Thus, in this embodiment, there is no need to provide a housing
portion shaped for receiving needle guidance portion 40 as these
components are provided with the transducer body. Shells 31 and 100
are preferably formed by injection molding, made of relatively
rigid plastic, which is easily sealable, less prone to rips or
tears than a conventional sleeve, and has an optional sleeve for
procedures that require a sterile cord.
[0072] With reference to FIG. 6, shell 100 includes an upper
portion 104, a lower portion 102 and a forward portion 106 encasing
probe 30. A forward surface 107 of forward end 106 allows acoustic
waves to pass through without appreciable attenuation. A rear end
110, formed by portions 102 and 104, provides an opening for a cord
connecting probe 30 to monitor 20. A raised region 108 includes a
slotted hole 108a sized to allow clip connector 44 to move freely
within a predetermined range of angles for purposes of adjusting
the angular orientation of a needle mounted to the probe, as
discussed earlier. In an alternative embodiment, clip connector 44
may be disposed so as to be recessed within, or flush with hole
108a so as to maintain sterility. Additionally, needle clip 200
(receivable on clip connector 44) may be provided with a skirt near
the end of post 224 so as to cover hole 108a for purposes of
maintaining sterility, but without obstructing rotation of needle
clip 200, as discussed earlier.
[0073] A pair of snap connectors 112, 114 or other suitable
fasteners are used to hold upper and lower portions 102, 104
together. FIG. 7 illustrates shell 100 before enclosing the probe
within. Shell 100 is a one-piece construction. Forward portion 106
is connected to upper portions 104 and lower portions 102 by living
hinges 106a and 106b. The design of shell 100 is such that forward
end 106 may be used as a container for acoustic coupling gel.
Hence, shell 100 may be provided with acoustic gel in container
area 116 and sealed by a removable lidstock.
[0074] The probe may be encased within shell 100 as follows. First,
a lidstock sealing the acoustic gel is pealed off. This exposes the
acoustic gel and allows the transmitting end of the probe to be
inserted into space 116. Next, portions 102 and 104 are brought
together by rotation about living hinges 106a, 106b until edges
102b, 102a, 104a and 104b mate together to form a sterile barrier.
In order to facilitate a good sterile barrier, cooperating lap
joints are formed on edges 102b, 102a, 104a and 104b. Male portions
112a, 114a and female portions 112b, 114b of snap connectors 112,
114 are then joined together by a snap fit. A protrusion is formed
on the male portions 112a, 114a so that when it is time to remove
the probe from shell 100, snap connectors 112, 114 may be
disengaged by pressing down on male portions 112a, 114a.
[0075] As discussed above and described in greater detail, below, a
disposable needle clip is used to secure a needle to the probe,
e.g., probe 30 and this needle clip is attached to probe 30 at clip
connector 44 after probe 30 is enclosed in shell 100. Needle clip
200, like shells 31 and 100, is sterile and stored sterilely until
use. Therefore, potential contamination is minimized when snapping
the shell onto the probe. The issue of maintaining sterility may be
addressed by two features. First, clip connector 44 may be disposed
so as to not extend beyond opening 35 or 108a of the completely
closed shells 31 and 100. This prevents contamination of the shell
opening by the non-sterile clip connector. Second, needle clip 200
may have a skirt that covers but does not touch the opening of hole
35 or 108a. This provides a second barrier and a tortuous path to
prevent potential contamination of the sterile shell. Ideally, a
needle clip and sterile shell are made available in
pre-manufactured sterile kits each containing a sterile gel packet,
a shell, at least one needle clip, and an optional sterile sleeve
for the cord. Thus, there is provided a sterile external surface
around the ultrasound probe and cord while allowing a needle clip
and clip connector to rotate and be monitored by a potentiometer
assembly.
[0076] Needle clip will now be described in greater detail with
reference to probe 30. Needle clip is preferably designed so that
the health professional may easily engage and disengage the needle
clip as well as secure and release, respectively, a needle from
probe 30 during the procedure. In particular, it is desirable that
the needle clip be designed so that probe 30 may be disengaged from
needle 50 so as to minimize any movement of the needle shaft while
it is embedded within the patient. First, second, third and fourth
embodiments of a needle clip will now be described with reference
to FIGS. 8-11.
[0077] With reference to FIGS. 8A, 8B and 8C, a first embodiment of
a needle clip 200 includes a first part 201 (FIG. 8A) and a second
part 202 (FIG. 8B). In another embodiment, parts 201 and 202 may be
a unitary, as opposed to a two-piece construction. A semi-circular
cradle 204 for receiving the shaft of a needle is formed on second
part 202. Second part 202 is sized for sliding engagement within a
holding portion 226 of first part 200. When inserted in holding
portion 226, ridges 212a, 212b engage with channels 228a, 228b,
respectively, which are formed on side walls 226a, 226b of holding
portion 226. A wall portion 208 of second part 202 has a surface
210 for abutment against surface 226c of holding portion 226 when
second part 202 is completely received in holding portion 226. This
contact between wall surface 210 and surface 226c ensures that
second part 202 will stay in holding portion 226. Flexible fingers
may be formed at an end of second part 202 for providing a positive
connection between first part 201 and second part 202. The
assembled needle clip 200 is secured to clip connector 44 by
placing a hollow post 224 formed on first part 200 over clip
connector 44. FIG. 8C illustrates the assembled needle clip 200
secured to clip connector 44 of probe 30.
[0078] Referring to FIGS. 8A and 8C, first part 201 includes a
fastening arm 216 secured to post 224 by a flex member 222. At a
first end 216a of fastening arm 216 a finger rest 220 is provided
and at an opposite end a cover 216b is disposed adjacent to the
holding portion 226. Flex member 222 has a curved shape which
allows it to be easily bent towards holding portion 224 by finger
pressure applied at finger rest 220. Clip connector 200 retains a
needle in cradle 204 by applying constant finger pressure at finger
rest 220. When finger pressure is applied to finger rest 220
(represented by force F in FIG. 8C), flex member 222 bends towards
holding portion 226, which causes cover 216b to extend over cradle
204 (direction d.sub.1 in FIG. 8C), thereby trapping the needle
shaft between cover 216b and cradle 204. When it is time to
separate the needle from the probe 30, the user simply removes the
finger pressure applied to finger rest 220, which causes flex
member 22 to return to its undeformed position, FIG. 8C, and cover
216b to move back to its initial position. By this action, the
needle shaft can be separated from probe 30 without any extra
movements, without the help of another health professional, without
disengaging any mechanical connection and hence with minimal or no
disruption to the needle shaft while it is embedded in the
patient.
[0079] Second and third embodiments of a needle clip will now be
described with reference to FIGS. 9 and 10. In the second
embodiment, there is a first part and a second part to the needle
clip, which can be secured to the clip connector 44 in the same
fashion as needle clip 200. In the third embodiment, there are
three parts to the needle clip. The same structure associated with
the holding portion, post and second part as described above for
needle part 200 is used in these other embodiments (alternatively,
a one-piece and two-piece construction may be chosen over a
two-piece and three-piece construction for these embodiments,
respectively). However, these other embodiments differ in the
structure and method of actuation associated with the fastening
arm. Accordingly, discussion of the second and third embodiments
will proceed with the understanding that the structure and
functionality of the remaining structure associated with the needle
clip will be readily understood in view of the discussion of the
first embodiment.
[0080] A second embodiment of a needle clip 400 will now be
described with reference to FIG. 9. In this embodiment, fastening
arm 416 (attached to post 226 at front and back sides thereof) has
a curved portion 417 that extends around holding portion 426 so
that cover 416b is disposed adjacent to, and on the opposite side
of cradle 204. Cover 416b extends over cradle 204 when finger
pressure is applied, as in the first embodiment. Actuation of cover
416b is accomplished by pressing downward on finger rest 420, which
causes cover 416b to move over cradle 204 (direction d.sub.3) so
that the needle shaft becomes trapped between cradle 204 and cover
416b. Needle may be removed form cradle 204 by releasing finger
pressure so that cover 416b displaces back to its starting position
(FIG. 9).
[0081] A third embodiment of a needle clip 500 will now be
described with reference to FIG. 10. In this embodiment, a
fastening arm 516 is slidingly received in a grooved section 522 of
first part 201 that is disposed adjacent to cradle 204. A flex
member 524 is attached to fastening arm 516 at a lower surface 516a
and is adapted to abut a surface 524a of probe 30, which causes
flex member 524 to flex towards finger rest 520 when finger
pressure is applied at finger rest 520. Before finger pressure is
applied, cover 516b does not cover cradle 204. When finger pressure
is applied, cover 516b extends over cradle 204, thereby trapping
needle shaft between cradle 204 and cover 516b. While finger
pressure is applied, flex member 524 is maintained in a flexed
state. When finger pressure is removed, flex member 524 will move
cover 516b back to its original position (i.e., not covering cradle
204) as it returns to its undeformed state. Needle shaft may then
be separated from probe 30. This embodiment, like the others
described, can be used to separate needle shaft from probe 30
without disengaging any mechanical connection and hence with
minimal disruption to the needle shaft while it is embedded in the
patient.
[0082] Certain modifications and improvements will occur to those
skilled in the art upon a reading of the foregoing description. By
way of example, the sterile shell can be made to work with any
existing ultrasound probe, providing a more convenient and operable
sterile covering than traditional probe sleeves. Also, the
cart-based compact ultrasound system can be modified to work with
other types of available probes, providing a more complete and user
friendly portable ultrasound system. Further, the present invention
can be configured to work with three-dimensional and
four-dimensional (real-time three-dimensional) ultrasound in
addition to the above described embodiment using real-time
two-dimensional ultrasound. All modifications and improvements have
been omitted herein for the sake of conciseness and readability but
are properly within the scope of the present invention.
* * * * *